The Helm manual says to pre-load the sway bar by jacking up the lower arms, then tightening the bar's bolts. All of the threads giving install instructions that I read skipped this step.

Is pre-loading necessary? What effect does it have on the effectiveness of the bar?

Thanks.
Tanq

 

Preloading the bar ensures the bolts are under normal load when they are torqued. The bolts might work loose if you don't do this step. There is no effect on performance unless the bolts come loose.

 

Although it should be noted that preloading does make a difference on many of the other suspension bolts (control arms, etc.). When torquing down bolts that secure with a bushing there is a definite set that is taken. The recommendation is to fully load the components (support the car with them) before final tightening.